morse



Jan. 6, 1942. 5 MORSE 2,269,161

' COLOR PHOTOGRAPHY Filed May 18, 1938 a Sheets-Sheet 1 Fig.1

DIFFUSER) 24 LIGHT T0 Pkocfss/ va RICHARD S. MORSE v INVENTOR L m/pub BYQ. YMZM ATTORNEYS Jan. 6, 1942. Q R 5, MORSE 2,269,161

COLOR PHOTOGRAPHY Filed May 18, 1938 3 Sheets-Sheet 2 Fig.2. 20 18 30 IL32 34 22 saw/v6 film/r BEAM I I JMLI/f .llllllrzflilll: ll||||h Fl' .3.20' 36 15 30/ g smmw/va BEAM RICHARD S.M0RsE INVENTOR ATTORNEYS PatentedJan. 6, 1942 1 ou rao STATES PATENT OFFICE 2,269,161, n n n n H COLORPHOTOGRAPHY I i Richards. Morse, Rochester, N.'Y., assignor to I .7Eastman Kodak Company, Rochester, N. Y., r

t 9 i e ApplicationMayi8,1938, Serial No.208',632

220mm. (c1; 95-2 This invention relates to color 7 photography andparticularly to the making of duplicates of color motion picture films.

It isan object the-invention to correct for errors in the colors oiacolor photograph when making a reproduction oithis photograph.

More specifically, the invention relates to three color photography andhasfor its objects to correct forerrors due to the color temperature, i.e. the departureirom whitelight, of the original illumination, tocorrectforshiits of color balance due toover or 'underexposure', to correct forerrors in relative sensitivity of the three sensitive layers and/ortocorrect for shifts of color balance due toerrors, in'processing, all ofwhich are errors-in thesteps of making the original photograph. r I

BroadlYLt-he invention has for its object the correction oierrors, whenreproducing by any color process such as a monopack, screen, lenticular,imbibitionor wash-oil relief process, a multicolor photograph made byany of these processes. More particularly, the present invention is mostuseful in the reproduction by a monopack process or an imbibitionprocess of a positive or negative photograph made by a monopack process.

According to the invention, correct color rendition of on originalsubject is provided by photographingthe subject and simultaneouslyphotographing a gray or neutral object by the same illumination andprocessing the two images by the same method. The two images must ofcourse be made on materials and processed under conditions whichmaterials and conditions are identical as far as any effect on colorbalance is concerned. The term "identical as used in the accompanyingclaims is intended to convey just the sense in which it is used here.Any departure of the photograph 01 the original from a correct renditionof the appearance it would have in white light due to errors inillumination or in processing, which latter errors include thoseintroduced by adjustment of. the reversal exposure, cause a similardeparture of the record of the gray or neutral colored objects from thedesired gray or neutral color. This latter departure is noted and acorrection therefor is introduced in reproducing the photograph of theoriginal.

Since the first photograph may be a negative or a positive, the phrase acorrect rendition of is used to include negative as well as positiverendition whereas the phrase could be entirely omitted if only theduplicating of a positive is the accompanying-claims, the termreproducing a photograph" is used to include dupli= eating a positivephotograph and printing a positive from a negative photograph. Similarlya fullcolor photograph may be either positive or negative whereas anatural color photograph can only be a positive. Either termdistinguishes from monotone photographic images.

According to a simplified embodiment of the invention, whereincorrection for errors in proc essing only are required, the gray orneutral colored record on the film may be produced by a flash exposureto a gray or neutral colored light.

More specifically the invention consists of placing on the original filmor a similar film, a.- record of a gray or neutral colored light whichmay be due to a fi'ash exposureor toa gray object adjacent to theoriginal subject. In the case of motion picture film this gray orneutral are not separate until after the record has been scanned, i. e.,a single white beam scanning the record is divided by a beamsplitter andsuitable filters into three primary colored beams.

This control of the relative intensities of the final positive imagesmay be provided by a light valve or similar means for controlling therelative amounts of the primary colors used in the printing orduplicating light. On the other hand the control may be provided byallowing the out- 49 put of the photoelectric cells to control the timeconcerned. Also in the present specification and of development, thetemperature of the developer or the concentration of the developer,affecting the corresponding color. When the reproduction is made by aprocess involving separate color separation negatives, the control ofthe color balance of the printing light consists specifically incontrolling the relative exposures of the three negatives. This controlof exposure may be obtained by controlling the intensity of the printinglight or by controlling the time of the printing exposure. In the caseof motion picture films, the control of intensity rather than of time ofexposure is more useful. The control of the intensity of an image inaccordance with some other factorincludes, direct, inverse, linear maybe either linearly or non-linearly. For clarity, some of the theoryunderlying the invention and the definitions of some of the terms usedin this specification and the accompanying claims will be brieflyoutlined.

White light is usually taken to mean daylight and it has been found thatcolor pictures aremcst satisfactory when they have an appearanceapproaching that which the original subject would have when illuminatedby white light, independent of the actual illumination of the originalsubject. Exceptions to this general rule need not be considered here.However, the broad statement that an object is reproduced as it wouldappear under white light will be taken to mean that the color renditionis the correct one which may or may not be slightly different from thatcorresponding to the appearance of the object when illuminated bywhitelight. In arranging color balance to get this proper rendering, thecolor of the light by which the reproduction is to be viewed must betaken into account. For example, motion pictures to be projected by anarc lamp require a difierent color balance than those to be projected bytungsten light.

A gray object or a gray light is one whose color appears gray to theaverage eye and contains equal proportions measured in suitable units ofthe three primary colors, red, green, and blue. The units employed musttake into account the various factors such as the relative responses ofthe human eye and other theoretical considerations which need not bediscussed here. For the purposes of the present invention, the object orlight used in producing the record which is to be scanned and which isto control the color correction need not be exactly gray but necessarilymust include large proportions of each of the three colors and hencethose colors which are slightly ofi gray such as tan, etc., may be used.Although the term neutral is sometimes taken in its strict sense to meanonly gray, it will be used in the present specification and theaccompanying claims to include those colors which are slightly off ofgray and ior which the spectral distribution is known. It is notuncommon for merchandisers of colored articles to use the term neutralin this general sense.

In three color photography, three color separation negativescorresponding to the primary colors are usually made and thencorresponding positives are made from these. Wash-oil relief processesfollow this procedure directly. Monopack. processes have the negativesin superimposed layers at some stage of the processing and the positivesare made by a reversal process the negatives being destroyed thereby.Some monopack processes are strictly negative positive processes ratherthan reversal processes. In lenticular and in screen processes thenegatives and positives are made up of juxtaposed elements. In any casethe final color print consists of three color separation positives inregister either superimposed or juxtaposed. There are also wellknowndifferences between subtractive and additive processes, but the aboveterminology appears to be sufiiciently complete to describe the moreuseful applications of the present invention.

Of course, the invention can well be applied to direct. positiveprocesses involving no stage wherein separation'negatives can be said toexist. It is also useful in making a positive print to correct forerrors in a negative color photograph 2,269,161 and/or non-linearcontrol. Similarly, inversely of an original. However, its greatest useis in duplicating, by a process effectively involving negatives at somestage, a positive photograph made by a similar process.

The present invention will be fully understood from the followingdescription of certain embodiments of it when read in connection withthe accompanying drawings, in which:

Fig. 1 shows an embodiment of the invention wherein the quality of theduplicating light is controlled.

Fig. 2 shows a. D. C. amplifying circuit suitvable for use with theinvention.

Fig. 3 shows an A. C. amplifying circuit suitable for use with-theinvention.

Fig. 4 shows an embodiment of the invention wherein the time of one ofthe processing steps is controlled.

Fig. 5 shows an embodiment of the invention wherein the time of printingexposur is controlled.

Fig. 6 illustrates the invention as applied to the duplicating of amonopack film by an imbibition or similar process involving separatecolor separation negatives.

In Fig. 1 a color motion picture film I! bearing a series of colorpictures II is reproduced on a similar film I2. The color processes usedfor films l0 and 12 need not be exactly the same. Adjacent to thepictures II, th film I0 is provided with a track or record l5 which wasprinted thereon before the processing of the film Hi. This record i5 maybe printed by the image of a gray or neutral colored object placedadjacent to the original subject or by a flash exposure to a white orneutral colored light of known spectral distribution. If, due to theprocessing,- or when a gray objectis illuminated by the same light asthe original, due to the color of the illumination, the color balance inthe pictures H is not correct, e. g. is too red, the record l5 will notbe a correct rendition of the gray or neutral color and in the examplementioned will be too red. If the film it is a negative one and too red,the print i2 will be printed correctly by increasing the amount of redtherein either by increasing the amount of red in the printin light oras will be discussed in connection with Fig. 4 by increasing the red (1.e. decreasing the bluegreen in a subtractive process) in the processing.If the film it is a positive one and too red, the duplicate 42 will bemade correctly by decreasing the amount of red therein.

The record 15' is scanned by the three primary colors by means of asuitable optical system shown as a light source I3, lenses l4 and IS, abeam splitter comprising prisms HR, ilG, HB and color filters 58R. (red)i-ilG (green), and EBB (blue). The relative intensities of the scanningbeams, i. e. the colors from the original are used to control thequality of the duplicating or printing light. The beams fallrespectively on photoelectric cells 19R, 19G, and 193 which throughsuitable electric circuits including amplifiers 203, 20G, and-2DR andbalancers 2|B,

' ZlG, and ZlRcontrol the light valves 22R, 22G,

This light source 25 together with suitable optical systems shown as alens 25 forms the printing or duplicating light.

Thus when the pictures II are too red, the record I5 is too red whichcauses the photoelectrio cell ISR to set up an electrical energy inexcess of normal which (when the pictures H are positive) closes downthe light valve 22R and reduces the amount of red in the light source'25 and when the pictures II are negative opens th valve 22R to increasethe red in the printing light source 25.

The electric circuits which control the light cells in accordance withthe electrical energies set up by. the photoelectric cells ISR, etc.,are provided with suitableadjustments whereby a correct color renditionin the record l5 gives the correct quality to the color of the secondarylight source 25. In Fig. 2, the electrical energy set up as a differenceof" potential across the points 30 and 3! is amplified by a suitabledirect current amplifier and produces across the points 32 and 33 apotentialwhich is modified according to the intensity of the scanningbeam. A suitable portion of this potential is taken oil at the points 34and 35 to operate a light valve 22 which may be of any suitable typesuchas a ribbon valve, a diaphragm, a galvanometer or any of thesuitable devices used in recording sound on film.

If the advantages of A. ,C. amplification are desired, an interrupter 35as shown in Fig. 3 may be placed in the scanning beam and an A. C.amplifier 20' may be used to produce an A. C. potential across thepoints 3'! and 38 modulated in accordance with the intensity of thescanning beam. Through a rectifier 38 and an adjusting means shown as avariable potential 40, this electrical energy is used to operate thelight valve 22.

Fig. 4 is similar to Fig. 1 and shows the manner in which the output ofthe photoelectric cells may beused to control the time of processing.The balancer circuit 2|B including the potentiometer circuit 343supplies zero potential when there is a normal blue component in therecord l5. An increase or decrease of the blue component causes apositive or negative output from the balancer 2IB which through acontact 55 engaging the resistance 34B and through electro-magnets 53and 54 and rectifiers 55 and 55 operates a double pole double throwswitch including a magnetically operated bar 51 and contacts 58, 59, 50and 5|. When there is a zero output from the balancer NB, the member 51remains in a neutral position permitting no current to pass through areversing motor 55 attached thereto. A positive output from the balancer2|B throws the switch in one direction and current through leads 52 froma suitable D. C. supply causes the motor 55 to rotate in one direction,and vice versa. The motor 55 operates a rack 53 and pinion 54 whichmoves a lever 52 up and down. One end of this member 52 carries thecontact 55 so that after the motor has rotated a certain amount thebalance in the balancer circuit 213 will be again established and theswitch 51 will move to the neutral position causing the 43, 44, etc. Inthe example shown, the processing vat 43 is the one which controls theintensity of blue in the final image. If there is an excess or blueintheoriginal pictures H and hence 5 in the track l5, a correction for thismay be introduced in duplicating or printing by controlling, i. e.either increasing or decreasing the amount of time in the bath 43. Ifthe original pictures II are negative and a positive print is being madetherefrom, the processing must be arranged to increase the amount ofblue in the print, i. e. decrease the amount of yellow in a subtractiveprocess. Fixed sprockets 45, 41, and 48 which drive the film through theprocessing vats are arranged so that as the film passes over thesesprockets and over the movable sprocket 45, the time which the film isin the bath 43 is, controlled by the height of the sprocket 45. Numerousequivalent methods of controlling the time may alternatively be used.The present invention is not specifically concerned with this detail.

If it is also desired to control the quality of the printing light, thismay be done through leads 5! in exactly the same manner as shown inFig. 1. This dual control is often necessary since changing one of thefactors only is not always sufficient to give the desired results.Although the invention is not primarily concerned with the reproductionof still color photographs and although the advantages such ascontinuous automatic control are not present in this case, Fig. 5illustrates how the invention may 'be applied to the making of stillduplicates and shows one feature which'is particularly useful in filter14, prints a color separation negative 15 from a color photograph 12.The color photograph 12 is provided with a gray portion 15 through whichlight from the lamp 10 passes through a color filter 11 andtherethrough. to

a photoelectric cell I8. The output of this photoelectric cell I8controls the time of exposure by turning off the lamp 10 after it hasbeen on for asuificient time. Alternatively, the photoelectric cell 18may be placed at the position 18 to receive light from the gray portion15 through the lens 13 rather than directly, but this is less practicalbecause of the loss of light. In operating the device, the lamp I0 isturned on through a relay 19' by closing a switch 80 which is heldclosed by an electro-magnet 82. At the same time a switch 8| is openedso that the output of the photoelectric cell 18 is used to establish acharge on a condenser 83 which is across the grid of an electrondischarge device I! which operates the relay 19'. when the charge on thecondenser 83 reaches a certain value, the valve 19 ceases to passcurrent and through the relay 19' turns out the lamp 10 and de-energizesthe magnet 82 thereby releasing the switch 88 and closing the switch 8|through which. the discharge from the condenser 83 leaks away, thusreturning the whole of the electric circuit to its original state.

Fig. 6 illustrates an extremely useful embodi- 7 ment of the inventionwherein a monopack film I5 is duplicated by an imbibition process inwhich separate color separation negatives are -made on sensitive films88, SI and 52. -The elements of this circuit are similar to those shownin Fig. l

and the arrangement is identical thereto except that the colorseparation negatives are printed separately in Fig. 6 and are printedsimultaneously on the monopack film l2 in Fig. 1.

' Having thus described the invention and the preferred embodiments withwhich it may be practiced, I wish to point out that it is not limited tothe arrangements shown but is of the scope of the appended claims.

What I claim and desire to secure by Letters Patent of the United Statesis:

l. The method of reproducing a multi-colored photograph prepared by apredetermined process which comprises preparing by the same process withidentical materials and identical processing conditions an approximatelyfull color photographic record of light of known spectral distribution,noting the departure of the record from a correct rendition of saiddistribution, reproducing said photograph and controlling the relativeamounts of the primary colors in the reproduction in accordance with theamount of said departure.

2. The method of duplicating a multi-colored positive photographprepared by apredetermined process which comprises preparing by the sameprocess with identical materials and identical processing conditions anapproximately natural color photographic record of a neutral coloredlight of known spectral distribution, noting the departure of the recordfrom said neutral color, duplicating said photograph and controlling therelative amounts of the primary colors in the duplicate in accordancewith the amount of said departure.

3. The method of printing a positive from a multi-colored negativephotograph prepared by a predetermined process which comprises preparingby the same process with identical materials and identical processingconditions an approximately full color negative photographic record of aneutral colored light of known spectral distribution, noting thedeparture of the record from a correct negative rendition of saidneutral color, printing the positive and controlling the-relativeamounts of the .primary colors-in the print in accordance with theamount of said departure.

4. The method of reproducing a multi-colored original as it would appearin white light which comprises preparing a colored photograph of theoriginal under given illumination conditions and by a predeterminedprocess, preparing by the same process with identical materials andidentical processing conditions and under the same illuminationconditions an approximately full color photographic record of an objecthaving a neutral color of known spectral distribution, noting thedeparture of the record from a correct rendition of said neutral color,reproducing said photograph and controlling the relative amounts of theprimary colors in the reproduction in accordance with the amount of saiddeparture.

5. The method of reproducing a multi-colored original as it wouldappear'in white light which comprises preparing a positive coloredphotograph of the original under given illumination conditions and by apredetermined process, preparing by the same process with identicalmaterials and identical processing conditions and under the sameillumination conditions an approximately natural color photographicrecord of an object having a neutral color of known spectraldistribution, noting the departure of the record from said neutralcolor, duplicating said positivephotograph and controlling the relative:amounts of the primary colors in the duplicate in accordance with theamount of said departure.

6. The method of reproducing a multi-colored original as it would appearin white light which comprises preparing a negative colored photographof the original under given illumination conditions and by apredetermined process, preparing by thesame process with identicalmaterials and identical processing conditions and under the sameillumination conditions an approximately full color negativephotographic record of an object having a neutral color of knownspectral'distribution, noting the departure of the record from a correctnegative rendition of said neutral color, printing a positive from thisnegative and controlling the relative amounts of the primary colors inthe positive in accordance with the amounts of said departure.

'7. The method of reproducing a multi-colored photograph prepared by apredetermined process which comprises preparing bythe same process withidentical materials and identical processing conditions an approximatelyfull color photographic record of a neutral colored light of knownspectral distribution, illuminating the record with light including thethree primary colors, producing from the photograph three colorseparation positive images in register, and controlling the relativeintensities of the three images in accordance with the relativeintensities of the three primary colors from the record.

8. The method of duplicating a positive multicolored photograph preparedby a predetermined process which comprises preparing by the same processwith identical materials and identical processing conditions anapproximately natural color photographic record of a neutral coloredlight of known spectral distribution, illuminating the record with lightincluding the three primary colors, producing from the positivephotograph three color separation negative images, producing from thesenegative images positive images in register and during at least one ofthe image producing steps, controlling the relative intensities of thethree images in accordance with the relative intensities of thethreeprimary colors from the record.

9. The method of printing a positive from a negative mul ti-coloredphotograph prepared by a predetermined process which comprises preparingby the same process with identical materials and identical processingconditions an approximately full color negative photographic record of aneutral colored light of known spectral distribution, illuminating therecord with light including the three primary colors, printing from thephotograph three color separation positive images in register andcontrollingthe relative intensities of the three images directly inaccordance with the relative intensities of the three primary colorsfrom the record.

10. The method of reproducing a multi-colored original as it wouldappear in white light which comprises preparing a colored photograph ofthe original under given illumination conditions and by a predeterminedprocess, preparing by the same process with identical materials andidentical processing conditions under the same illumination conditionsan approximately full color photographic record of an object havingneutral color of known spectral distribution, illuminating the recordwith light including the three primary colors, producing from thephotograph three colored separation positives in register andcontrolling the relative intensities of the three images in accordancewith the intensities of the three primary colors from the record.

11. The method of reproducing a multi-colored photograph prepared by apredetermined process which comprises preparingby the same process withidentical materials and identical processing conditions an approximatelyfull color photographic record of a neutral colored light of knownspectral distribution, illuminating the record with light including thethreeprimary colors, establishing electric energies corresponding to theintensities of the three colors from the record, producing from thephotograph three colored separation positive images in register andcontrolling the relative intensities of the three images in accordancewith the corresponding electric energies.

12. The method of duplicating a positive colored photograph prepared bya predetermined process which comprises preparing by the same processwith identical materials and identical processing conditions anapproximately natural color photographic record of a neutral coloredlight or known spectral distribution, illuminating the record with lightincluding the three primary colors, establishing electric energiescorresponding to the intensities of the three colors from the record,producing from the photograph three colored separation negative images,producing from these negative images positive images in register andcontrolling the relative intensities of the three positive imagesinversely in accordance with the corresponding electric energies.

13. The method of printing a positive from a negative multi-coloredphotograph prepared by a predetermined process which comprises preparingby the same process with identical materials and identical processingconditions an approximately iull color negative photographic record of aneutral colored light of known spectral distribution, illuminating therecord with light including the three primary colors, establishingelectric energies corresponding to the intensities of the three colorsfrom the record, printing from the photograph three coloredseparationpositive images in register and controlling the relativeintensities of the three images directly in accordance with thecorresponding electric energies.

14. The method of reproducing a multi-colored original as it wouldappear in white light which comprises preparing a coloredphotograph oithe original under given illumination conditions and by a predeterminedprocess, preparing by the same process with identical materials andidentical processing conditions and under the same illuminationconditions an approximately full color photographic record of an objecthaving neutral relative intensities of the three primary colors in colorof known spectral distribution, illuminating which comprises preparingby the same process with identical materials and identical processingconditions an approximately full color photographic record of graylight, noting the departure of the record from a correct rendition ofgray, reproducing said photograph and controlling the relative amountsof the primary colors in the reproduction in accordance with the amountof said departure.

16. The method of duplicating a positive multicolored photographprepared by a predetermined process which comprises preparing by thesame process with identical materials and identical processingconditions an approximately natural color photographic record of graylightjnoting the departure of the record from gray, duplicating saidphotograph and controlling the relative amounts of the primary colors intheduplicate in accordance with the amount of 'said departure.

17. The method of printing a positive from a negative multi-coloredphotograph prepared by a predetermined process which comprises preparingby the same process with identical materials and identical processingconditions an approximately full color negative photographic. record ofgray light, noting the departure of the record from a correct negativerendition of gray, printing said positive from the negative andcontrolling the relative amounts of the primary colors in the positivein accordance with the amount of said departure.

18. The method of reproducing a multi-colored original as it wouldappear in white light which comprises preparing a colored photograph ofthe original under given illumination conditions and by a predeterminedprocess, preparing by the same process with identical materials andidentical processing conditions and under the same illuminationconditions an approximately full color photographic record of a grayobject, noting the departure of the record from a correct rendition ofgray, reproducing said photograph and controlling the relative amountsof the primary colors in the reproduction in accordance with the amountof said departure.

19. The method of duplicating a colored motion picture mm prepared by apredetermined process which comprises preparing by the same process andadjacent to the picture area on the film an approximately natural colorphotographic record of a gray light, scanning the record with the threeprimary colors, controlling the the duplicating light inversely inaccordance with the intensities of the corresponding colors from therecord.

20. The method'of reproducing a colored motion picture iilm prepared bya predetermined process which comprises preparing by the same processand adjacent to the picture area on the film an approximately full colorphotographic record of a gray light, printing three separate sensitivelayers from the film through three primarycolor filters to form colorseparation negatives, scanning [the record with the three primary colorsand controlling the relative intensities oi. the printing exposuresinversely in accordance with the intensities of the corresponding colorsfrom the record.

21. The method of reproducing a multi-colored photograph prepared by apredetermined process which comprises preparing by the same process withidentical materials and identical processing conditions an approximatelyfull color photographic record of light of known spectral distribution,noting the departure of the record from 'a correct rendition of saiddistribution, recolorphotographing said photograph-color processing therecolor-photograph and controlling said color processing in accordancewith said departure.

22'. The method of reproducing a multicolored photograph prepared on acolor photographic material by'a predetermined process which comprisespreparing on the same material ltO one side of the photograph areasimultaneously with the preparation oi said photograph and by the sameprocess an approximately full color photographic record of neutral lightof known spectral distribution, scanning the record with the threeprimary colors, reproducing the photograph and controlling the relativeamounts of the primary colors in the reproduction in accordance with thecorresponding colors from the record.

l RICHARD S. MORSE.

